Escapement operating arrangement for typewriters



June 28, 1966 H. DECKER 3,258,101

ESCAPEMENT OPERATING ARRANGEMENT FOR TYPEWRITERS Filed Sept. 9, 1963 4 Sheets-Sheet 1 INVENTOR. z /erb e r) p 1 H. DECKER 3,258,101

ESCAPEMENT OPERATING ARRANGEMENT FOR TYPEWRITERS June 28, 1966 4 Sheets$heet 2 Filed Sept. 9, 1963 FIG 4 June 28, 1966 H. DECKER ESCAPEMENT OPERATING ARRANGEMENT FOR TYPEWRITERS Filed Sept. 9, 1963 4 Sheets-Sheet 5 June 28, 1966 DECKER 3,258,101

ESCAPEMENT OPERATING ARRANGEMENT FOR TYPEWRITERS Filed Sept. 9, 1965 4 Sheets-Sheet 4 INVENTOR. i e er EM wk iv United States Patent 3,258,101 ESCAPEMENT OPERATING ARRANGEMENT FOR TYPEWRITERS Herbert Decker, Nurnberg, Germany, assignor to Max Grnndig, Bavaria, Germany Filed Sept. 9, 1963, Ser. No. 307,679 Claims priority, application Germany, Sept. 12, 1962,

3 Claims. 61. 197-s2 The present invention relates to an escapement operating arrangement for typewriters and similar business machines and more particularly to apparatus in which a step of a paper carriage is effected whenever a type bar is actuated to imprint a sheet on the platen of the paper carriage.

In manually operated typewriters, the type action and the type bar are accelerated by the manual force applied by the operator to a key, whereas in electric typewriters, the force is provided by a motor which may rotate a power roll driving type actions whose associated key was actuated by the operator.

At the impact point of the type on the platen the energy stored in the moving type is used for making an impression, and it is evident that the impact energy is the amount of energy applied to the type bar less losses caused by friction. However, in addition to the friction losses, energy is required for operating auxiliary devices in the typewriter during each type action operation. For example, the ribbon must be transported and raised, and the universal bar must be actuated in order to cause operation of the escapement mechanism by which the paper carriage is controlled to perform a single step whenever a type action is actuated to move the type bar toward the platen.

The energy required for transporting and raising the ribbon is small and substantially constant. However, the force required for actuating the escapement mechanism is far greater and not the same for each actuation. The type bar operates the universal bar which is connected to the escapement mechanism in order to retract a pawl of the escapement mechanism from the rack bar of the paper carriage. The engagement between the rack bar and the pawl serves to stop the paper carriage against the action of the strong carriage spring, and in the stopped position of the carriage, the friction between the escapement pawl and the rack bar is substantial.

The force required for sliding the escapement pawl out of engagement with the rack bar is not always constant. The friction force which has to be overcome depends on the pressure of the rack bar tooth against the escapement pawl.

If the escapement mechanism is operated by an actuated type action while the carriage is at a standstill, a certain friction force has been overcome. However, during consecutive actuation of several type lever actions, and depending on the typing speed, it may occur that the rack bar booth has bounced back from the escapement pawl after a carriage step so that the full force of the carriage spring is not effective to cause a frictional engagement between the rack bar tooth and the escapement pawl. In this event, a much smaller force is derived from the actuated type bar during its movement toward the platen. On the other hand, and again depending on the time period between successive actuations of type lever actions, the escapement mechanism may be actuated at the moment at which a tooth of the rack bar of the release substantially different forces are required for actuating the escapement mechanism even for a constant tension of the carriage spring, and the variation of such forces is entirely unpredictable. As a result, a typist operating a manual typewriter with a constant finger pressure, or an electric typewriter in which the necessary force is always applied to all type lever actions, Will not produce exactly uniform impressions since from the energy applied to the moving type bar, different amounts of energy are detracted in accordance with the pressure which happens to prevail between the rack bar tooth of the carriage and the escapement pawl when the same is pulled back to release the carriage for a step.

This undesirable condition particularly occurs if the weight of the carriage is very great since the inertia is increased, and also if the carriage spring is highly tensioned in accordance with a desired high typing speed. Furthermore, power operated electric typewriters have adjustments for driving type actions associated with type faces of different size with adjusted forces to achieve uniform imprints of all characters. The energy applied to each type action is calculated to be sufiicient to produce a good impression even when the greatest resistance of the escapement mechanism is to be overcome. In the event that the escapement mechanism offers only little resistance as explained above, the force applied to the type bar is too great, and a heavier imprint is made which detrimentally affects the appearance of the typed text.

It is one object of the invention to overcome this disadvantage of typewriters according to the prior art, and to provide an escapement operating arrangement which has no influence on the impact force of the types.

Another object of the present invention is to operate the escapement mechanism during the return movement of the type from the platen to the position of rest.

Another object of the invention is to operate an escapement mechanism of a typewriter in such a manner that the type bar moving toward the platen to produce an imprint, need not provide any force for actuating the escapement mechanism.

Another object of the invention is to prevent any influence of the variable forces required for actuating escapement mechanism on the impact force of the type bars and on the impressions produced by the same.

Another object of the invention is to provide an escapement operating arrangement of simple construction which can be provided in standard typewriters without substantial constructive changes.

Another object of the invention is to move the paper carriage of a typewriter one step during each movement of an actuated type bar from a printing position to a position of rest.

Another object of the invention is to provide the force required for actuation of an escapement mechanism by storing the necessary energy in spring means during movement of the type bar toward the platen, so that the energy stored in the spring means is used for actuating the escapement mechanism during the return of the type bar from the printing position to a position of rest.

Another object of the invention is to provide a typewriter in which uni-form imprints are produced irrespective of the weight of the carriage, the tension of the carriage spring, and the typing speed.

With these objects in view, the present invention provides an escapement mechanism for stepwise moving a carriage with a platen; a device including a type bar movable toward and away from the platen; and means for connecting the device with the escapement mechanism only during movement of the type bar away from the platen. As a result, the escapement mechanism is actuated after the imprint has been made by the type, and consequently cannot influence the imprint so that all imprints are uniform, irrespective of the variable resistance of the escapement mechanism against actuation.

Since the escapement mechanism is operated after the imprint has been made by the type bar, the impact force of the type bars will not depend at all on the variable resistance of the escapement mechanism.

In conventional typewriters, all type actions, and more particularly the type bars, shift a universal bar against the action of a spring. In accordance with the present invention, the universal bar causes actuation of the escapement mechanism While returning under the action of the spring after the type bar has made an imprint and while the type bar returns to the position of rest.

In accordance with the present invention, the means which connect the type bar with the escapement mechanism include coupling means which are controlled by the type bar during the movement of the same toward the platen to assume a coupling position, while the biasing means of the universal bar effect through the coupled coupling means the actuation of the escapement mechanism while the type bar returns to its position of rest. Consequently, energy is taken from the type bar during movement toward the platen only for the purpose of placing the coupling means in the coupling position, and this energy does not depend on conditions prevailing at the escapement mechanism, but is constant, so that the impressions made by the type are uniform. The variable amounts of energy required for operating the escapement mechanism, are provided by the biasing means of the universal bar during the return movement of the type bar.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation together with additional objects and advantages thereof, will be best understood from the following description of speciiic embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a fragmentary sectional view illustrating one embodiment of the invention in a position of rest;

'FIG. 2 is a fragmentary, partially sectional view, taken in the direction of the arrow II in FIG. -1;

FIG. 3 is a fragmentary sectional view corresponding to FIG. 1 but illustrating an operative position of the device;

FIG. 4 is a fragmentary view, partially in section, taken in the direction of the arrow IV in FIG. 3;

FIG. 5 is a fragmentary plan view illustrating a modified embodiment of the invention in a position of rest;

FIG. 6 is a fragmentary plan view illustrating the embodiment of FIG. 5 in another operative position; and

FIG. 7 is a fragmentary side view illustrating the embodiment of FIG. 5.

Referring now to the drawings, and more particularly to FIGS. 1 to 4, a set of type bars 3, of which only one is shown, is mounted for turning movement about a shaft 2 in a support segment 1. Each type bar has a projection 4 cooperating with a curved universal bar which is biased by leaf spring 6. The curved universal bar 5 is connected by arm 7 to the yoke of a U-shaped member whose legs 9 are pivotally mounted on support segment 1. Arm 7 has a transverse projection formed with a bore which is slidably guided along a rod 1-1 mounted on support segment 1. A spring 12 abuts projection 10 and a fixed washer at the end of rod 11 so that arm 7 is urged to the right as viewed in FIG. 1, acting on the universal bar 5 in the same direction as leaf spring 6.

A downwardly dependent arm 13 is an integral part of projection 10 and has a free end pivotally connected to a connecting rod 14 whose other end is connected to the arm 15 of a U-shaped bridge 116 which is mounted on a shaft '17 for turning movement. Consequently, when type bar .3 is moved from the position shown in FIG. 1 to the position shown in FIG. 3 in solid lines, member 16 will turn in clockwise direction. Arm '15 of member 16 carries a stud 18 on which a coupling member 19 is mounted in such a manner that it is not only turnable, but also tiltable in a transverse direction. When U-shaped member 16 turns in clockwise direction, coupling member 19 moves downward in direction of the arrow 0 while being guided on a horizontal pin 21 which passes through a longitudinally extending slot 20 in coupling member 19. A slanted spring 2 2 is secured to coupling member 19 and to U-shaped member 16, and urges coupling member 19 to tilt in clockwise direction as viewed in FIG. 2. An abutment 23 is secured to the free end of coupling member '19 and forms a shoulder on the same. Abutment member 23 is omitted in FIGS. 1 and 3 for the sake of clarity, and only indicated by a dash and dot line.

The carriage of the typewriter supports a platen 36, and has a rack bar 33 fixedly secured thereto. A pair of escapement members 25 and 27 includes pawls 31 and 32 which cooperate with rack bar 33. A shaft 28 passes through elongated openings 29 and 30 in escapement members 25 and 27 so that the same can turn about shaft 28, but also perform a shifting movement in the direction of the movement of rack bar 33 with the carriage. A tension spring 34 is attached to each escapement member,

and urges the respective escapement member to turn in counterclockwise direction indicated by arrow a as viewed in FIG. 2 to a position in which pawls 31 and 32 engage rack bar 33 and stop the carriage which is urged to move to the left as viewed in FIG. 2 by a conventional spring, not shown.

When a key, not shown, is operated and the type action including type bar 3 is actuated, type bar 3 moves in counterclockwise direction out of the position shown in FIG. 1 to the position shown in solid lines in FIG. 3 so that its projection '4 displaces the universal bar in the direction of the arrow 1) together with arm 7 and arm 13 against the combined action of leaf spring 6 and coil spring 12. Rod 14 transmits the movement to the U- shaped member 16 so that arm :15 turns downward and moves coupling member 19 in the direction of the arrow 0.

In the position of rest illustrated in FIG. 2, the end of coupling member 19 abuts the end face of a coupling arm 26 of escapement member 27. When coupling member 19 moves to the position shown in FIG. 4, it slides off the end face of coupling arm 26 and is urged by spring 22 to perform a transverse tilting movement until abutment 23 abuts the end face of coupling arm 26. Since spring 34 biases escapement member 27 to turn counterclockwise, coupling arm 26 abuts the free end of coupling member 119 in the coupling position shown in FIG. 4.

It will be seen that during the forward movement of type bar 3 towards platen 36, the escapement means 25 and 27 were not connected to the type action, and that the forward motion of type bar 3 was used for coupling the type action with the escapement mechanism. Consequently, no force was provided by the type action to operate the escapement mechanism before the imprint was made, but only a small force is required for sliding coupling member 19 oil. the end face of coupling arm 26.

After the type of type bar 3 has hit the platen, it returns to its initial position of rest under the action of springs 6 and 11 which urge the universal bar 5 against type bar 3. Members 5, 7, 13, and 14 move to the right, as viewed in FIGS. 1 and 3, and turn U-shaped member 16 in counterclockwise direction so that coupling member 19 moves in a direction opposite to the direction of the arrows 0. Since coupling member 19 is coupled to the coupling arm 26 of escapement member 27, escapement member 27 is turned in clockwise direction and pawl 32 releases rack bar 33 so that the carriage moves in the direction of the arrow d under the action of the conventional spring, not shown. After a single step, such movement is stopped by pawl 31 which is urged by its spring 34 into engagement with a recess in rack bar 33. Escapement member 25 is free to perform such a movement in counterclockwise direction since its coupling arm 24 is free, and not engaged by coupling member 19. This is due to the fact that spring 34 acting on escapement member 25 pulls escapement member 25 to the right until shaft 28 abuts the left end of the elongated opening 29 in escapement member 25.

As soon as pawl 31 engages rack bar 33, the pull of the carriage spring is effective to shift escapement member 25 to the left in the direction of the arrow d so that shaft 28 is located at the right end of the elongated opening 29 so that escapement member 25 cannot move farther to the left, and stops rack bar 33 with the carriage.

In the initial position of FIG. 2, the pull of the carriage spring had urged escapement member 27 to the left so .that coupling member 19 was tilted to the left against the action of spring 22. In the position of FIG. 4, the carriage spring is still effective to hold escapement member 27 in a position in which shaft 28 abuts the right end of elongated opening 30 for holding the carriage arrested. However, when the carriage performs a step while abutting pawl 31 of escapement member 25, the pressure on pawl 32 is relieved, and its spring 34 has sufiicient power to shift escapement member 27 with coupling arm 26 to the right as viewed in FIG. 4 until the left end of slot 30 abuts shaft 28 and coupling arm 26 slides off the end face of coupling member 19 so that escapement member 27 is free to turn in counterclockwise direction to a position in which its end face is spaced from coupling member 19, as is shown for coupling arm 24 in FIG. 2. Pawl 32 is now in a position of readiness to stop the carriage after the next following step. Consequently, the escapement members 25 and 27 are alternately operative to release the carriage for one step, and to stop the carriage after one step.

The force for operating the escapement members is provided by springs 12 and 6, and a carriage step takes place during the return movement of the type action and of type bar 3 so that variations of the necessary force have no influence on the impact force of the type. During the forward movement of the type bar 3 toward the platen, no motion is transmitted from the type action to the escapement mechanism 25, 27, 34, 33, but the only force required is the small force for overcoming the friction between the coupling member 19 and one of the coupling arms 24, 26. This force is constant, while different forces are required for operating the escapement mechanism depending on the moment in which the escapement mechanism is released, as has been explained above. Tests have proven that the impressions produced by the type are completely uniform, irrespective of the pressure applied to the keys, and of the speed at which the keys and type actions, and thereby the escapement means, are operated.

In the second embodiment of the invention an anchortype escapement mechanism of known construction is operated in accordance with the present invention during the return movement of the type bar.

A universal bar 40 is mounted for pivotal movement on a pair of pivot points 41 and 42, and has an operating arm 4% pivotally connected to a coupling member 43 by a pivot means 44. A fixed pin or roller 46 guides coupling member 43 for longitudinal movement, and coupling member 43 is biased by spring 47 to turn in clockwise direction about pivot means 44 so as to slidingly abut guide pin 46. Another spring 45 is mounted on arm 40a, and abuts a plate 45a of the frame to urge universal bar 40 and coupling member 43 to move in a direction opposite to the direction of the arrow e in FIG. 5. The movement of the universal bar 40 is blocked by the type bar 3 while the same is in the position of rest,

6 and the corresponding position of rest of coupling member 43 is shown in FIG. 5.

Coupling member 43 has a coupling part 48 transversely projecting from a lateral edge of coupling member 43 and cooperating with a coupling part 49 projecting from one arm of an escapement member 52 whose pawl 54 cooperates with a toothed escapement wheel 55 which is secured to a gear 56 mounted on shaft 57 and cooperating with the rack bar of the carriage in a conventional manner.

Escapement member 52 is supported on a shaft 51 which passes through an elongated opening 50 in escapement member 52 so that the same is mounted for turning movement and also for shifting movement in longitudinal direction. A spring 53 is secured to the frame and escapement member 52 and urges the same to move to the right. In the position of FIG. 5 pawl 54 engages the escapement wheel 55 which is urged by the carriage spring to turn in the direction of the arrow h in FIG. 6.

Shaft 51 supports another escapement member 58 whose pawl 59 cooperates with the escapement wheel 55. A spring 60 connects two arms of the escapement members 52 and 58, and turns the same in opposite directions until a stop projection 61 on escapement member 58 abuts escapement member 52.

When a key, not shown, is operated and actuates a type action, the type bar of any selected type action presses against the universal bar 40 in the direction of the arrow e so that the same turns and shifts coupling member 43 in the same direction. Coupling projection 48 slides along coupling projection 49, and coupling member 43 is slightly tilted in counterclockwise direction while spring 47 is tensioned. As soon as coupling projection 48 has passed coupling projection 49, spring 47 pulls coupling member 43 back in clockwise direction so that coupling projection 48 is now located behind coupling projection 49 in a coupling position in which the universal bar is coupled to the escapement mechanism. LID. the meantime the type has reached the platen, ,and produced the imprint. During the return movement of the type, spring returns universal bar 40 to its initial position pulling coupling member 43 in the direction opposite to the direction of the arrow 2 in FIG. 5. When coupling projections 48 and 49 abut each other, escapement member 52 is turned in the direction of the arrow 1 in FIG. 6 against the action of spring 53. Since spring 60 connects escapement member 58 to escapement member 52, escapement member 58 also turns in counterclockwise direction about shaft 51 until pawl 59 abuts a tooth of escapement wheel 55, as shown in FIG. 6. Due to the turning movement of escapement member 52 in clockwise direction pawl 54 has released escapement wheel 55 so that spring 53 can pull escapement member 52 in the direction of the arrow g in FIG. 6 to a position in which shaft 51 abuts the left end of the elongated opening and coupling projection 49 releases coupling projection 48. FIG. 6 illustrates the position directly preceding this disengaged position and shows the extremities of coupiing projections 43 and 49 still in engagement. The carriage spring, not shown, acting on the carriage and on the rack bar turns gear 56 with escapement wheel in counterclockwise direction as indicated by the arrow h and just before the carriage has completed the one step, the disengaged escapement member 52 is turned in clockwise direction by spring 53 to engage the next tooth of the escapement wheel 55. The angular movement of escapement member 52 is transmitted by projection 61 to escapement member 58 so that pawl 59 releases escapement wheel 55 and assumes the position shown in FIG. 5.

Pawl 59 of escapement member 58 stops the carriage only very shortly during a step, and as is conventional in an anchor-type escapement mechanism. The carriage has performed one step, and is held by pawl 54 in the position of FIG. 5. It will be seen that escapement member 52 corresponds to the free escapement member, and escapement member 58 corresponds to the fixed escapement member of a standard typewriter escapement mechanism. As in the embodiment described with reference to FIGS. 1 to 4, only a small force for coupling coupling member 43 with escapement member 52 is required during the forward movement of the type bar toward the platen and carriage, while the greater and variable forces required for operating the escapement mechanism are provided by a spring 45 during the return movement of the type, so that the impact force and the quality of the impression is not influenced by variable forces, but remains constant.

It will be understood that each of the elements described above or two or more together, may also find a useful application in other types of escapement mechanisms for typewriters differing from the types described above.

While the invention has been illustrated and decribed as embodied in an arrangement in which the escapement mechanism of a typewriter carriage is operated during the return movement of the type from the platen to a position of rest, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis the foregoing will so fully reveal the gist of the present invention that others can be applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed and desired to be secured by Letters Patent is:

1. In a typewriter, in combination, a carriage having a platen and a rack bar, and being biased to move in one direction; an escapement mechanism including a gear meshing with said rack bar and a toothed escapement wheel connected to said gear for rotation therewith, a pair of escapement members, means for mounting said escapement members for turning movement, and one of said escapement members also for shifting movement, a spring connecting said escapement members and urging the same to turn in opposite directions, and a stop secured to the other escapement member and abutting said one escapement member in a selected angular position of said escapement members, each escapement member having a pawl portion adapted to cooperate with said escapement wheel, and said one escapement member having a coupling part; a type bar movable toward and away from the platen of said carriage; a universal bar operatively connected with said type bar to move in a first direction during movement of said type bar toward said platen; spring means urging said universal bar to move in a second opposite direction when said type bar moves away from said platen; a coupling member connected with said universal bar for movement in said first and second direction, and being mounted for movement in a direction transverse to said first and second directions, said coupling member having a part cooperating with said coupling part of said one escapement member; a spring urging said coupling member to move in said transverse direction to a position in which said coupling parts cooperate and are coupled, a stop limiting movement of said coupling member under the action of said spring; said coupling member, said coupling parts, and said one escapement member being arranged and constructed in such a manner that movement of said coupling member in said first direction causes engagement between said coupling parts and transverse displacement of said coupling member against the action of the spring and away from said stop whereupon said spring returns said coupling member in said transverse direction to a coupling position in which said coupling parts are coupled during movement of said coupling member in said second direction for turning said one escapement member to a position releasing said escapement wheel whereby a carriage step is effected during the movement of said type bar away from said platen.

2. An arrangement as set forth in claim 1 wherein said universal bar is mounted for turning movement and has an arm pivotally connected to said coupling member.

3. An arrangement as set forth in claim 2 wherein said coupling member moving in said second direction coupled to one escapement member turns said escapement member to a position releasing said escapement wheel so that said spring of said escapement mechanism shifts said one escapement member so that the same moves from a position in which said shaft abuts one end of said bearing opening to a shift position in which said shaft abuts the other end of said bearing opening whereby said coupling parts of said coupling member and of said one escapement member are separated and disengaged.

References Cited by the Examiner UNITED STATES PATENTS 995,515 6/1911 Yaw "197-86 1,054,998 3/1913 S-tickney 197-86 2,536,619 1/1951 Yeeger 197 s5 DAVID KLEIN, Primary Examiner.

ROBERT E. PULFREY, Examiner.

ERNEST T. WRIGHT, Assistant Examiner. 

1. IN A TYPEWRITER, IN COMBINATION, A CARRIAGE HAVING A PLATEN AND A RACK BAR, AND BEING BIASED TO MOVE IN ONE DIRECTION; AN ESCAPEMENT MECANISM INCLUDING A GEAR MESHING WITH SAID RACK BAR AND A TOOTHED ESCAPEMENT WHEEL CONNECTED TO SAID GEAR FOR ROTATION THEREWITH, A PAIR OF ESCAPEMENT MEMBERS, MEANS FOR MOUNTING SAID ESCAPEMENT MEMBERS, MEANS FOR MOUNTING SAID SAID ESCAPEMENT MEMBERS ALSO FOR SHIFTING MOVEMENT, A SPRING CONNECTING SAID ESCAPEMENT MEMBERS AND URGING THE SAME TO TURN IN OPPOSITE DIRECTIONS, AND A STOP SECURED TO THE OTHER ESCAPEMENT MEMBER AND ABUTTING SAID ONE ESCAPEMENT MEMBER IN A SELECTED ANGULAR POSITION OF SAID ESCAPEMENT MEMBERS, EACH ESCAPEMENT MEMBER HAVING A PAWL PORTION ADAPTED TO COOPERATE WITH SAID ESCAPEMENT WHEEL, AND SAID ONE ESCAPEMENT MEMBER HAVING A COUPLING PART; A TYPE BAR MOVABLE TOWARD AND AWAY FROM THE PLATEN OF SAID CARRIAGE; A UNIVERSAL BAR OPERATIVELY CONNECTED WITH SAID TYPE BAR TO MOVE IN A FIRST DIRECTION DURING MOVEMENT OF SAID TYPE BAR TOWARD SAID PLATEN; SPRING MEANS URGING SAID UNIVERSAL BAR TO MOVE IN A SECOND OPPOSITE DIRECTION WHEN SAID TYPE BAR MOVES AWAY FROM SAID PLATEN; A COUPLING MEMBER CONNECTED WITH SAID UNIVERSAL BAR FOR MOVEMENT IN SAID FIRST AND SECOND DIRECTION, AND BEING MOUNTED FOR MOVEMENT IN A DIRECTION TRANVERSE TO SAID FIRST AND SECOND DIRECTIONS, SAID COUPLING MEMBER HAVING A PART COOPERATING WITH SAID COUPLING PART OF SAID ONE ESCAPEMENT MEMBER; A SPRING URGING SAID COUPLING MEMBER TO MOVE IN SAID TRANSVERSE DIRECTION TO A POSITION IN WHICH SAID COUPLING PARTS COOPERATE AND ARE COUPLING, A STOP LIMITING MOVEMENT OF SAID COUPLING MEMBER UNDER THE ACTION OF SAID SPRING; SAID COUPLING MEMBER, SAID COUPLING PARTS, AND SAID ONE ESCAPEMENT MEMBER BEING ARRANGED AND CONSTRUCTED IN SUCH A MANNER THAT MOVEMENT OF SAID COUPLING MEMBER IN SAID FIRST DIRECTION CAUSES ENGAEMENT BETWEEN SAID COUPLING PARTS AND TRANSVERSE DISPLACEMENT OF SAID COUPLING MEMBER AGAINST THE ACTION OF THE SPRING AND AWAY FROM SAID STOP WHEREUPON SAID SPRING RETURNS SAID COUPLING MEMBER IN SAID TRANSVERSE DIRECTION TO A COUPLING POSITION IN WHICH SAID COUPLING PARTS ARE COUPLED DURING MOVEMENT OF SAID COUPLING MEMBER IN SAID SECOND DIRECTION FOR TURNING SAID ONE ESCAPEMENT MEMBER TO A POSITION RELEASING SAID ESCAPEMENT WHEEL WHEREBY A CARRIAGE STEP IS EFFECTED DURING THE MOVEMENT OF SAID TYPE BAR AWAY FROM SAID PLATEN. 